NEW APPROACHES IN CLINICAL-CHEMISTRY - ONLINE ANALYTE CONCENTRATION AND MICROREACTION CAPILLARY ELECTROPHORESIS FOR THE DETERMINATION OF DRUGS, METABOLIC INTERMEDIATES, AND BIOPOLYMERS IN BIOLOGICAL-FLUIDS

The use of capillary electrophoresis (CE) for clinically relevant assa ys is attractive since it often presents many advantages over contempo rary methods. The small-diameter tubing that holds the separation medi um has led to the development of multicapillary instruments, and simul taneous sample analysis. Furthermore, CE is compatible with a wide ran ge of detectors, including UV-Vis, fluorescence, laser-induced fluores cence, electrochemistry, mass spectrometry, radiometric, and more rece ntly nuclear magnetic resonance, and laser-induced circular dichroism systems. Selection of an appropriate detector can yield highly specifi c analyte detection with good mass sensitivity. Another attractive fea ture of CE is the low consumption of sample and reagents. However, it is paradoxical that this advantage also leads to severe limitation, na mely poor concentration sensitivity. Often high analyte concentrations are required in order to have injection of sufficient material for de tection. In this regard, a series of devices that are broadly termed ' analyte concentrators' have been developed for analyte preconcentratio n on-line with the CE capillary. These devices have been used primaril y for non-specific analyte preconcentration using packing material of the C-18 type. Alternatively, the use of very specific antibody-contai ning cartridges and enzyme-immobilized microreactors have been demonst rated. In the current report, we review the likely impact of the techn ology of capillary electrophoresis and the role of the CE analyte conc entrator-microreactor on the analysis of biomolecules, present on comp lex matrices, in a clinical laboratory. Specific examples of the direc t analysis of physiologically-derived fluids and microdialysates are p resented, and a personal view of the future of CE in the clinical envi ronment is given. (C) 1997 Elsevier Science B.V.